Unit 5

Medical Biotechnology II

Lesson 1

• Introduction: movie “Contagion” • Discussion: Is this movie realistic with regards

to how diseases in spread, how governments respond, and the availability of vaccines?

• http://www.movie2k.to/Contagion-watch-movie-1033665.html

Lesson 2

• Infectious• Classification, transmission, prevention• Lecture; Read and study powerpoint• Work with a partner and develop review

questions • Whole class discussion of review questions.• Gram Stain Lab: Normal Flora• Case Study: Childbed fever

Infectious Disease Classification

• Epidemiology: the study of when and where diseases occur and how they are transmitted.

• Pathology: The study of disease• Etiology: The study of the cause of a disease• Infection: Colonization of the body by

pathogens• Disease: An abnormal state in which the body

is not functioning normally.

Infectious Disease Classification• Normal Flora and the Host Normal Flora or Normal

Microbiota: The normal bacteria found in or on your body; mostly nonpathogenic

Normal flora can become pathogenic when it colonizes areas of the body that it is not normally found in; ex. E. coli in the bladder instead of the intestines.

Infectious Disease Classification

• Normal Microbiota and the Host

• Locations of normal microbiota on and in the human body.

Infectious Disease Classification

• Where does normal flora come from?

• Environment, family members etc.

• Fetus in the uterus is germ free.

• At birth, Lactobacilli from the vagina colonize the baby’s digestive tract.

Infectious Disease Classification

• Transient Flora and the Host

• Transient Flora: Bacterial changes of normal flora due to seasonal changes (temperatures, etc.) or age and activity.

Infectious Disease Classification Can normal flora benefit the host? Microbial antagonism: how microbes

inhibit the growth of other microbes, usually by competition (e.g. bacteriocins).

Bacteriocins: chemicals produced by bacteria to inhibit the growth of other bacteria (normal flora produce a lot of this).

Probiotics are live microbes applied to or ingested into the body, intended to exert a beneficial effect.

Infectious Disease Classification• Symbiosis• Symbiotic relationship: organisms

living in a close, intimate relationship with each other.– Commensalism, one organism is

benefited and the other is unaffected. (Normal flora).

– Mutualism, both organisms benefit. (Normal flora).

– Parasitism, one organism benefits at the expense of the other. (Infectious disease)

Infectious Disease Classification• Pathogen• A pathogen or infectious agent is a

biological agent that causes disease or illness to its host.

• The term is used for agents that disrupt the normal physiology of a cell, fungus, animal or plant.

• A pathogen can be viral, bacterial, fungal, or a prion.

• A “primary pathogen” is defined as an organism capable of causing disease in a healthy person with a normal immune response.

• A “secondary pathogen” is an infectious agent that causes a disease that follows the initial infections.

Infectious Disease Classification• Opportunistic Pathogen• Opportunistic Pathogen :

Potential pathogenic organisms that do not ordinarily cause disease in the normal habitat of a healthy person.

• When these organisms get into an area where they are not normally found and cause disease.

• All normal flora are have the capacity to be an opportunist in a compromised host (one without normal immune response).

Transmission Infectious Disease

• Reservoirs of Infection• For a disease to perpetuate itself, there must

be a continual source of disease. This continual source is referred to as the reservoir.

• Reservoirs are classified as either human, animal or nonliving.

Transmission Infectious Disease

• Reservoirs of Infection Reservoirs of infection are continual sources

of infection. Human — AIDS, gonorrhea

Carriers may have inapparent infections or latent diseases.

Animal Zoonoses. Diseases that occur primarily in animals. Example

Rabies, Lyme disease, toxoplasmosis, influenza Nonliving —

Soil: Botulism, tetanus Water: Cholera

Transmission Infectious DiseaseContact transmission.

1. Direct contact: Person to person transmission by physical contact. This includes touching, kissing and sexual intercourse.

2. Indirect contact Disease is transmitted from a nonliving object (fomite) to a host.

- Fomites may include eating utensils, toys, towels, door knobs, etc.

3. Droplet transmission. Mucous droplets from coughs sneezes laughing or talking. Droplet travels less than one meter from the reservoir to host.

- Example Whooping cough, Influenza, the Common Cold.

Transmission Infectious Disease

Transmission Infectious Disease

• Vehicle: Transmission by an inanimate reservoir

- Food: E. coli gastroenteritis (fecal/oral) - Water: Cholera (fecal/oral) - Airborne: Anthrax• Vectors: Arthropods, especially fleas, ticks,

and mosquitoes. - Plague, Lyme disease

Transmission Infectious Disease

Prevention

• Vaccines• Antimicrobial drugs• Handwashing • Sanitation of fomites and water

supplies• Prepare and store food properly• Control pests (insects and

rodents)• Quarantine

Lesson 3• Part 1 – Stages of Infection• Read powerpoint online• Work with a partner to develop review questions.• Whole class discussion questions.• Read article about stages of infection, traditional medical tests, and molecular

biology tests used to diagnose.• Part 2 – Epidemiology• Read SARS time line (Refer to handout)• What types of activities occur during an epidemic• Read powerpoint online.• Write a one paragraph description of the important elements in an

epidemiological investigation.• View video –SARS The True Story• Class discussion

Stages of Infection• How Infectious Agents

Cause Disease• Production of poisons,

such as toxins and enzymes, that destroy cells and tissues.

• Direct invasion and destruction of host cells.

• Triggering responses from the host’s immune system leading to disease signs and symptoms.

Stages of Infection

1. Entry of Pathogen – Portal of Entry

2. Colonization – Usually at the site of entry

3. Incubation Period– Asymptomatic period – Between the initial

contact with the microbe and the appearance of the first symptoms

Stages of Infection

4. Prodromal Symptoms– Initial Symptoms

5. Invasive period– Increasing Severity of

Symptoms – Fever – Inflammation and Swelling – Tissue Damage – Infection May Spread to Other

Sites – Acme

Stages of Infection

6. Decline of Infection - Improvement in

symptoms

7. Convalescence

Diagnostic Tests- Traditional

• Isolation of Pathogens from Clinical Specimens

• If a physician suspects a bacterial infection, samples of infected body fluids or tissues are collected from the patient.

• Samples may include blood, spinal fluid, pus, sputum, urine, or feces.

• A swab may be used to sample the infected area.

Diagnostic Tests - Traditional

• Isolation of Pathogens from Clinical Specimens

• The swab is then inoculated onto the surface of an agar plate or put into a tube of liquid medium.

• The bacteria is grown and isolated.

Diagnostic Tests-Traditional

• Isolation of Pathogens from Clinical Specimens

• The bacteria is identified by growth dependent rapid identification systems.

• These systems contain a battery of biochemical tests.

Diagnostic Tests-Traditional• Isolation of Pathogen from

Clinical Specimen• Identified pathogens are then

tested for sensitivity to antimicrobial agents.

• Drug sensitivity testing guides antimicrobial therapy for the patient.

• Small wafers with antibiotics are placed on a plate of bacteria. Large zones of no bacterial growth indicated antimicrobial sensitivity.

Diagnostic Tests- Traditional• Serology Tests for Antibody or

Antigen (Bacterial & Viral)• The agglutination of antigen coated

or antibody coated latex beads with a complimentary antibody or antigen is a typical method of rapid diagnosis.

• Blood serum from the patient is used in this test.

• If , for example, a patient has antibody to a particular infectious agent, the antibody will bind to the antigen coated latex beads.

• The suspension becomes visibly clumped. http://www.youtube.com/watch?v=hRzOwSTkF0s

• (first 3 min)

Diagnostic Tests- ELISA

• Enzyme Linked Immunoassay (viruses)-ELISA• A target antigen is bound to a solid phase such as the

plastic on a microplate.• A patient’s blood serum is added to the microplate.• Antibody in the serum will bind to the antigen.• The well in the plate is washed with an enzyme tagged

antihuman antibody which binds to the patient antibody.

• A substrate for the enzyme is added and a color reaction occurs .

Diagnostic Tests- ELISA

• Microplate Antibody/antigen/ Enzyme complex

Molecular Diagnostic Tests• Nucleic Acid Hybridization• To identify a bacteria or virus, a

species specific nucleic acid probe is needed.

• Probes are a single strand of DNA with a sequence unique and complimentary to the gene of interest.

• If a clinical specimen contains the microorganism of interest, the probe will bind to the microorganism’s gene DNA sequence.

• The double stranded DNA is detected because the probe is labeled with a radioactive, fluorescent, or enzyme tag.

Molecular Diagnostic Tests• PCR• There are PCR tests available to extract

DNA or RNA from bacteria or viruses.• The PCR method uses species specific

primers for targeted DNA or cDNA.• The DNA is then amplified.• Detection of the gene sequence can be

done by gel electrophoresis.• An alternative to electrophoresis is the use

of PCR machines with precision optics monitors.

• The primer has a fluorescent label and the monitor plots the uptake of the primer. If the primer has been used, this indicates the presence of the microorganism.

Epidemiology• In investigating an outbreak, speed is essential, but getting the right answer is

essential, too. To satisfy both requirements, epidemiologists approach investigations systematically, using the following 10 steps:

• Prepare for field work• Establish the existence of an outbreak• Verify the diagnosis• Define and identify cases• Describe and orient the data in terms of time, place, and person• Develop hypotheses• Evaluate hypotheses• Refine hypotheses and carry out additional studies• Implement control and prevention measures• Communicate findings• The steps are presented here in conceptual order. In practice, however, several

may be done at the same time, or they may be done in a different order. For example, control measures should be implemented as soon as the source and mode of transmission are known, which may be early or late in any particular outbreak investigation.

Epidemiology

• Step 1: Prepare for Field Work• Before leaving for the field:• Research the disease and gather the supplies/

equipment needed• Make necessary administrative and personal

arrangements for such things as travel. • Consult with all parties to determine your role in the

investigation and who your local contacts will be.

Epidemiology

• Step 2: Establish the Existence of an Outbreak• Verify that a suspected outbreak is indeed a real

outbreak. • Some of the cases will be associated with a true outbreak

with a common cause, some will be unrelated cases of the same disease, and others will turn out to be unrelated cases of similar but unrelated diseases.

• Before you can decide whether an outbreak exists (i.e., whether the observed number of cases exceeds the expected number), you must first determine the expected number of cases for the area in the given time frame.

Epidemiology

Epidemiology• Step 3: Verify the Diagnosis• In addition to verifying the existence of an outbreak early in

the investigation, you must also identify as accurately as possible the specific nature of the disease.

• Goals in verifying the diagnosis are two-fold. - First, ensure that the problem has been properly diagnosed—that it really is what it has been reported to be. - Second, for outbreaks involving infectious or toxic-chemical agents, be certain that the increase in diagnosed cases is not the result of a mistake in the laboratory.

Dx

Epidemiology

• Step 4: Define and Identify Cases• Establish a case definition. Your next task as an

investigator is to establish a case definition, or a standard set of criteria for deciding whether, in this investigation, a person should be classified as having the disease or health condition under study. A case definition usually includes four components:

• clinical information about the disease, • characteristics about the people who are affected, • information about the location or place, and • a specification of time during which the outbreak

occurred.

Epidemiology• Step 5: Describe and Orient the Data in Terms of Time, Place, and

Person• After data collection, characterize an outbreak by time, place, and

person. This step may be performed several times during the course of an outbreak. Characterizing an outbreak by these variables is called descriptive epidemiology,

• This step is critical- First, by becoming familiar with the data, you can learn what information is reliable and what is not. - Second, you provide a comprehensive description of an outbreak by showing its trend over time, its geographic extent (place), and the populations (people) affected by the disease. This description lets you begin to assess the outbreak in light of what is known about the disease and to develop causal hypotheses.

Epidemiology (descriptive)

Epidemiology• Step 6: Develop Hypotheses• In real life, we begin to generate hypotheses to

explain why and how the outbreak occurred when we first learn about the problem. But at this point in an investigation, after you have interviewed some affected people, spoken with other health officials in the community, and characterized the outbreak by time, place, and person, your hypotheses will be sharpened and more accurately focused.

• The hypotheses should address the source of the agent, the mode (vehicle or vector) of transmission, and the exposures that caused the disease. Also, the hypotheses should be proposed in a way that can be tested.

Epidemiology

• Step 7: Evaluate Hypotheses• The next step is to evaluate the credibility of

your hypotheses. There are two approaches you can use, depending on the nature of your data: 1) comparison of the hypotheses with the established facts and 2) analytic epidemiology, which allows you to test your hypotheses with cohort and case control studies.

Epidemiology (cohort study)

Epidemiology• Step 8: Refine Hypotheses and Carry Out Additional Studies• Additional epidemiological studies

When analytic epidemiological studies do not confirm your hypotheses, you need to reconsider your hypotheses and look for new vehicles or modes of transmission. This is the time to meet with case-patients to look for common links and to visit their homes to look at the products on their shelves.

• Also, confirmation from laboratory findings can be valuable.

Epidemiology

Step 9: Implementing Control and Prevention Measures

• Even though implementing control and prevention measures is listed as Step 9, in a real investigation you should do this as soon as possible.

• Control measures, which can be implemented early if you know the source of an outbreak, should be aimed at specific links in the chain of infection, the agent, the source, or the reservoir.

Epidemiology

• Step 10: Communicate Findings• Your final task in an investigation is to

communicate your findings to others who need to know. This communication usually takes two forms: 1) an oral briefing for local health authorities and 2) a written report

Epidemiology

• SARS – The True Story http://www.youtube.com/watch?v=MXPaee0uEQM

• Case study: SARS

Lesson 4

• Origin of SARs and evolution of the virus• Work in groups of 4. Read powerpoint and

web articles about origin of SARS virus and viral evolution.

• Discuss and respond to questions.• Write a short essay explaining how natural

selection occurred with the SARS virus.

Origin of SARS & Evolution

• Visit the following websites for the origin of SARS:

• http://www.abc.net.au/science/features/sars/default.htm

• http://learn.genetics.utah.edu/archive/sars/index.html

Origin of SARS and Evolution

• Visit the following websites for the evolution of SARS:

• http://www.smartplanet.com/blog/science-scope/study-shows-how-swiftly-infectious-viruses-evolve/12136

• http://www.scientificamerican.com/article.cfm?id=sars-evolution-traced

• http://learn.genetics.utah.edu/archive/sars/index.html

Identification of SARS virus

• 6 weeks after the outbreak of SARS, CDC identified the SARS virus as a coronavirus via electron microscopy.

• http://www.smithsonianmag.com/science-nature/Stopping_a_Scourge.html

• This is what they saw:

Identification of SARS virus

• Coronavirus• Are single stranded RNA viruses• Replicate in the cytoplasm of the

host cell.• Spherical 60- 220 nm in size.• Contain club shaped

glycoproteins on their surfaces. The virus looks like it has a crown.

• Largest genome of any RNA viruses; 29,700 base pairs.

Identification of SARS virus

• Replication• The plus strand RNA enters the

cytoplasm.• Only RNA polymerase is translated

directly from the virus genome to protein.

• RNA polymerase makes a negative RNA strand.

• Negative RNA strand is a template to make monocistronic (only codons for protein) m RNA that is used in translation.

Identification of SARS virus• The second step in identification

of the virus was to discover the DNA sequence of the virus.

• Three months after the outbreak, Canada’s Michael Smith Genome Sciences Center in British Columbia sequenced the SARS coronavirus.

• The DNA sequence is located in GenBank.

• http://www.msfhr.org/news/features/2009/03/speed_demons

Identification of SARS virus• Bioinformatics• DNA isolates were taken from SARS

virus and compared to DNA isolates from other coronaviruses and other strains of SARS viruses.

• By comparing SNP (single nucleotide polymorphism) among the DNA isolates, researchers were able to classify the virus and create a phylogenetic tree.

• Researchers also discovered that four proteins were responsible for pathogenesis of SARS: spike (S) protein; small envelope (E) protein; membrane (M) protein; and nucleocaspid (N) protein.

Patient Diagnostics -SARS

• The DNA sequencing and research led to two frequently used tests to help diagnose SARS in patients.

1. RTPCR – Real Time Reverse Transcriptase PCR

2. ELISA – Enzyme linked immunoassay

Patient Diagnostics• RTPCR• Enables researchers to quantify amplification reactions in real time.• A specialized thermo cycler with a laser scan beams light through the PCR tube.• The PCR product is labeled with a fluorescent tag.• The amount of fluorescent light produced after each cycle is printed on a computer

readout.• This allows for quantification of the number of PCR products produced after each

cycle.• For diagnosis of SARs, patient tissues and body fluids can be used directly. The

primers used in the test are specific for cDNA made from the viral genome.• http://www.youtube.com/watch?v=kvQWKcMdyS4

Patient Diagnosis• ELISA• The SARS antigen is bound to a

microplate.• The patient’s blood serum with SARS

antibodies is introduced.• The patient SARs antibody binds to the

SARS antigen.• A second antibody with an enzyme

attached combines with the SARS antibody/antigen complex.

• When a substrate is added,t he well in the microplate turns color with a positive reaction .

• http://highered.mcgraw-hill.com/sites/0072556781/student_view0/chapter33/animation_quiz_1.html.

Patient Diagnostics• ViroChip• A DNA microarray test system called ViroChip enables doctors to

screen for the type of virus present in a patient, if they do not know the virus type.

• A ViroChip has 22,000 DNA sequences on it and identifies a variety of different viruses.

• http://www.nytimes.com/2008/10/07/health/research/07conv.html

Lesson 5

• Immunology• Work in groups of 4. • Read powerpoint, discuss, and respond to

questions.• Complete chart of immune responses.• Whole class discussion of responses.• Write a 5 minute commercial or skit about the

immune system.• Present skit or commercial.

Immunology• Two types of immunity• Innate or Non-specific Immunity• Adaptive or Acquired Immunity

Immunology

• 3 Lines of Defense in immunity

• Barriers at body surfaces (innate)

1. Intact skin and mucous membranes

2. Infection fighting tears and saliva.

3. Normal bacterial flora outcompete pathogens.

4. Flushing effects of tears, urination, diarrhea.

Immunology• 3 Lines of Defense• Non-specific Responses (Innate)1. Inflammation

a. Fast acting white blood cells; neutrophils, basophils, eosinophils.b. Macrophagesc. Complement proteins and other infection fighting substances.

2. Organs with phagocytic functions i.e. lymph nodes.

Immunology

• 3 Lines of Defense• Immune Responses

(Adaptive or Specific)• T cells and B cells• Communication

signals and chemical weapons ( antibodies, complement proteins etc.)

Innate or Non –Specific Immunity• Innate Immunity – Non specific

responses• Innate immunity is a non specific

attack against any cell or particle that is not self.

1. Antimicrobial agents2. Phagocytic cells3. Nonphagocytic cells4. Natural killer cells 5. Inflammation and Fever

Innate or Non-Specific Immunity

• Innate - Antimicrobial agents• Antimicrobial agents are chemicals or molecules

that act to deter or destroy microorganisms. Some of them act in conjunction with physical barriers.

There are 3 types:1. Interferon2. Interleukins3. Complement

Innate or Non-specific Immunity• Interferon• Interferons are a large group of

proteins that acts as signals both during innate and adaptive immune responses.

• Interferon is produced early in viral infections by a cell.

• The interferon will not keep the cell from viral infection but it is released and warns other cells to synthesize antiviral cell surface proteins.

• http://www.youtube.com/watch?v=3qFu6Fv4cJk&feature=related

Innate or Non-specific Immunity

• Interleukins• Interleukins are another

class of proteins which are produced by cells of the immune system.

• Tumor necrosis factor (TNF) , a type of interleukin, stimulates cells to create an inflammatory response.

• TNF cells can also kill tumor cells.

Innate or Non-specific Immumity

• Complement: a family of 20 different proteins.• Found in blood serum and protect the body

from infection.• Works together with other components of the

innate and adaptive immune systems.• Generally, complement is inactive.• In the presence of an antigen, complement

becomes activated.

Innate or Non-specific Immunity• Complement• Complement is activated in 4 general and non

specific ways.:• Some complement proteins coat the surface

of a pathogen so phagocytes can engulf them.• Other complement proteins lyse the cell wall

of microorganisms• Other complement proteins trigger the

release of histamine which increases inflammation by dilating blood vessels and increasing capillary permeability.

• Some complement proteins attract lymphocytes.

• http://highered.mcgraw-hill.com/sites/0072556781/student_view0/chapter31/animation_quiz_1.html

Innate or Non-specific Immunity• Innate – Phagocytic Cells• Sometimes an infectious agent avoids

physical barriers and antimicrobial agents in the body.

• A 3rd line of defense is available.• Phagocytic cells engulf microorganisms

in digestive vacuoles and break down cells.

• Phagocytic cells contain many enzymes: lysozyme to breakdown peptidoglycan, proteases to break down proteins, nucleases to break down DNA and RNA, and lipases to break down lipids.

Innate or Non-specific Immunity

• Phagocytic Cells• There are 2 types of phagocytic cells:1. Stationary phagocytes – reside along blood

vessel walls and in connective tissue2. Wandering phagocytes – circulate in the

blood.• Both types are made in the bone marrow

Innate or Non-specific Immunity• Stationary phagocytes• Macrophages are large phagocytic cells.• Made in the bone marrow, they circulate

in the blood for a few days and are called monocytes at this stage.

• Monocytes are released into connective tissue and are now referred to as macrophages.

• Macrophages are scavenger cells. They engulf:

1. Microorganisms2. Dead body cells3. Cancer cells4. Cells infected with viruses.• The life span of a macrophage is from a

few months to many years.

http://www.youtube.com/watch?v=m6qJ69wcSnc

Innate or Non-specific Immunity• Wandering Phagocytes• Wandering phagocytes are white

blood cells called monocytes and neutrophils.

• There are 4,000-6,000 neutrophils/mm3 of blood. They account for 65% of all white cells.

• In a bacterial infection, neutrophil numbers can double.

• Neutrophils are mobile. They can squeeze through capillaries and into cells; they can enter the spinal column to fight meningitis.

• http://hippocampusbiology.blogspot.com/2009/03/bacteria-can-run-but-they-cant-hide.html

Innate or Non-Specific Immunity• Innate – Nonphagocytic Cells• Eosinophils – White blood cells that secrete enzymes

that attack parasitic worms; reside in blood.• Basophils - White blood cells that contain heparin

(stops blood from clotting) and histamine (vasodilator which promotes blood flow to tissues). Play a role in inflammation and allgergies. Reside in blood.

• Mast Cell - Cells residing in many tissues that contain heparin and histamine. Look like basophils but come from different cell line. Important in inflammation.

Innate or Non Specific Immunity

Mast Cell

Eosinophil Basophil

Innate or Non-specific Immunity

• Innate – Natural Killer Cells• Are not phagocytic.• Are a white blood cell called a

lymphocytes• Attach to cell surfaces and produce

enzymes that destroy antibody covered cells that have been infected with microorganisms or viruses.

• Also able to destroy cancer cells. • http://www.youtube.com/watch?v=

HNP1EAYLhOs

Innate or Non-specific Immunity• Innate – Inflammation• Inflammatory response is a major component of the

innate immune system.• In inflammation:1. When tissue is injured or microorganisms enter the

tissue, mast cells release chemicals called histamine.

Innate or Non-specific Immunity• Inflammation2. The chemicals spark the mobilization of various defenses.a. Histamine induces blood vessels to dilate and increases blood flow

to the injured tissue.b. Blood plasma leaks out of the blood vessels to the affected tissues.c. Phagocytic cells squeeze out of the blood vessels and migrate to

the tissue.d. Increased blood flow, fluid, and cells produce redness, heat, and

swelling of tissues.

Innate of Non-specific Immunity

• Inflammation3. The major results of inflammation is to

disinfect and clean injured tissue.a. Phagocytic cells engulf bacteria and

body cells killed by them.b. Many phagocytic cells die in this process

and they are engulfed and digested.c. Pus that accumulates at the injury site

consists of dead cells and fluid from leaking capillaries.

Innate or Non-specific Immunity

• Inflammation• Inflammation helps prevent the

spread of infection to surrounding tissues.

• Clotting factors and platelets pass into the tissues from the blood and form local clots to seal off the infected region.

• The damaged tissue begins to repair. http://www.sumanasinc.com/webcontent/animations/content/inflammatory.html

Innate or Non-specific Immunity• Innate- Fever• During some infections, fever occurs.• Fever is induced by toxins released by

microorganisms.• The increase in body temperature:1. Kills some microorganisms.2. Increases inflammation.3. Stimulates phagocytic activity.4. Stimulates adaptive (acquired)

immune response.5. Reduces iron concentration in blood

and limits amount of iron available to microorganisms.

Adaptive or Acquired Immunity

• Adaptive immunity is a complex set of interactions that is highly specific against one type of antigen.

• Whereas innate immunity reacts to a variety of pathogens, adaptive immunity must be primed by the presence of an antigen.

• Adaptive immunity either attacks a specific antigenic invader directly or it produces antibodies.

• There are two types of adaptive immunity:1. Cell mediated immunity2. Humoral immunity

Adaptive or Acquire Immunity• Cell mediated immunity

involves a type of lymphocyte called a T (thymus) cell. T cells work against infections caused by fungus and protozoans. Also, they are important in eliminating cancer cells.

• Humoral immunity involves a type of lymphocyte called a B cell. B cells protect against viruses and bacteria in body fluids by producing antibodies.

Adaptive or Acquired Immunity

• Both T cells and B cells originate from stem cells in the bone marrow.

• B cells continue to mature in the bone marrow.

• T cells are carried from the bone marrow to the thymus gland to become specialized.

• Both T cells and B cells have the ability to recognize self from antigen.

Adaptive or Acquired Immunity• Cell Mediated Immunity• T cells after maturation are

moved to the lymphatic system.• T cells are primarily involved in

attacking cells directly.• While T cells are maturing, they

develop the ability to recognize specific antigens (Non-self)

• For T cells to go into action, they need the antigen presented to them.

Adaptive or Acquire Immunity

• Cell mediated immunity• All cells have surface glycoproteins

call the Major Histocompatibilty Complex (MHC).

• In humans, the MHC is called HLA (human leukocyte antigen).

• These classes of molecules mark our cells as self.

• Invading cells have an MHC and this marks them as foreign.

Adaptive or Acquire Immunity• Cell mediated immunity• Cells like macrophages recognize

foreign (MHC) cells and ingest them.• Macrophages(or other cells) then

display antigenic fragments from the microorganism on their cell surfaces.

• Macrophages displaying antigens are called antigen presenting cells (APC).

• T cells bind to the macrophage/antigen complex and this activates the T cell.

• T cells will then proliferate and carry out their functions.

Adaptive or Acquire Immunity• Cell mediated immunity• There are 2 types of T cells:1. CD8 or cytotoxic T cells2. CD4 or helper T cells

Adaptive or Acquire Immunity• Cell mediated immunity• CD8 cells• CD8 cells respond to foreign

antigens on the cell’s surface by binding to the antigenic MHC on the invading cells and directly killing them.

• CD8 cells release perforin, a protein that creates pores on the invading cells membrane. Water and ions flow into the cells and the cell lyses.

• Cancer cells, foreign cells from a transplant or graft, pathogen infected cells, and virus infected cells are targeted by CD8 cells.

http://www.theimmunology.com/animations/Cytotoxic.T.Cell.htm

Adaptive or Acquired Immunity

Adaptive or Acquired Immunity• Cell mediated immunity• CD4 cells• CD4 cells that have been activated by an APC secrete

cytokines, a protein that stimulates other lymphocytes.• If B cells have contacted an antigen, the signal from the CD4

cell differentiates the B cell into an antibody producing cell.• CD4 cells also play a role in stimulating CD8 cells to

proliferate. • http://highered.mcgraw-hill.com/sites/0072507470/studen

t_view0/chapter22/animation__t-cell_dependent_antigens__quiz_2_.html

Adaptive or Acquired Immunity

• Humoral Immunity• B cells are involved in humoral immunity.• B cells produce antibody. The antibody

produced by a B cell is specific for a particular antigen.

• There are two types of B cells:1. Plasma Cells2. Memory Cells

Adaptive or Acquired Immunity• Humoral immunity• Plasma Cells• A plasma cell encounters an

antigen and secretes a specific antibody.

• Plasma cells are activated when they encounter an antigen and are stimulated by helper T cells.

• Plasma cells can produce more than 10 million antibodies in an hour.

Adaptive or Acquired Immunity• Humoral immunity• Memory Cells• Not all activated B cells become

plasma cells.• Some become memory cells and

produce small amounts of antibody after an infection has been eliminated.

• If the same microorganism is encountered again, the memory cells change to plasma cells and begin producing antibody.

• This enables the immune system to attack rapidly and aggressively if there is re-infection.

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter24/animation__the_immune_response.html

Adaptive or Acquire Immunity

• Antibodies1. Antibody structure and function2. Disposal of antibody/antigen complex.

Adaptive or Acquired Immunity

• Antibody structure and function• Antigens that elicit an antibody

response are typically a protein or polysaccharide surface component of microbes.

• The antibody does not bind to the total antigen.

• A small accessible portion of antigen called an epitope or antigenic determinant is available for binding to the antibody.

• A single antigen has several epitopes and each epitope binds to a different antibody.

Adaptive or Acquired Immunity

• Antibody structure and function.• Antibodies are globular serum

proteins called immunoglobulins.• There are two antigen binding

sites for specific epitopes on an antibody.

• Each antibody consists of 4 polypeptide chains. 2 identical heavy chains and 2 identical light chains.

Adaptive or Acquired Immunity• Antibody Structure and

Function• At the 2 tips of the antibody

are variable regions (on light and heavy chains).

• The amino acid sequence varies from antibody to antibody.

• The variable region gives the antibody specificity for an antigen.

• The binding of the epitope and the binding site is similar to an enzyme substrate reaction.

Adaptive or Acquired Immunity• Antibody structure and

function• The tail of the antibody is

formed by the constant region.• The constant region is

responsible for distribution of the antibody within the body and for mechanisms that mediate the disposal of the antibody/antigen complex.

• There are 5 types of heavy chain constant regions: IgA, IgG, IgM, IgD, and IgE.

Adaptive or Acquire Immunity

• Disposal antibody/antigen complex• The binding of antibody to antigen creates

complexes that must be disposed.• Three types of disposal1. Neutralization/Opsonization2. Agglutination/ Precipitation3. Complement fixation

Adaptive or Acquire Immunity

• Disposal antibody/antigen complex• Neutralization/Opsonization• In neutralization, the antibody binds to the antigen.• The microbe covered in antibodies is phagocytized

by macrophages.• Opsonization is similar to neutralization.

Compounds called opsins bind to antibody/antigen complexes and this enhances the ability of the macrophage to phagocytize the microorganism

Adaptive or Acquired Immunity

• Disposal antibody/antigen complex• Agglutination• Agglutination is possible because antibodies have 2 antigen

binding sites.• One site can attach to one bacteria and the second site can

attach to a second bacteria.• When thousands of antibodies behave in this way, a clumping

of the microorganisms occurs.• Precipitation is similar to agglutination as clumping occurs.• In precipitation, the antigens cross link and form a precipitate.• Both processes are followed by macrophage phagocytosis.

Adaptive or Acquired Immunity• Disposal antibody/antigen complex• Complement Fixation• Antibody/antigen complexes

activate a complement cascade.• Complement consists of 20 proteins

and in the cascade one type of complement triggers the production of the next type in a series of reactions.

• Completion of the complement cascade results in lysis of viruses and pathogenic cells or opsonization.

• http://highered.mcgraw-hill.com/sites/0072556781/student_view0/chapter31/animation_quiz_1.html

Lesson 6

• ELISA Lab – SARS virus• Conduct ELISA test.• Write lab report• Refer to your handouts

Lesson 6

• Vaccines• Read article: How do vaccines work?• Discussion: How is this related to discussion of immune

system• Lecture- Types of vaccines (biotechnology)• Whole class review with questions of vaccine types.• Video: Mothers who do not vaccinate their children.• Read and review article on causal relationships between

vaccines and adverse effects.• Discussion: Should childhood vaccination be mandatory?

Lesson 5

• Vaccines

Vaccines

• How do vaccines work?• http://www.healthychildren.org/English/safet

y-prevention/immunizations/pages/How-do-Vaccines-Work.aspx?nfstatus=401&nftoken=00000000-0000-0000-0000-000000000000&nfstatusdescription=ERROR%3a+No+local+token

• http://www.historyofvaccines.org/content/how-vaccines-work

Vaccines• Vaccination has proven effective

against fighting diseases caused by microorganisms.

• Infectious disease is one of the major causes of death worldwide. 60% of children worldwide under the age of 4 die from infectious disease.

• The world’s first vaccine was made by Edward Jenner in 1796. He discovered that the live cowpox virus could be used to immunize patients against smallpox.

Vaccines

• Vaccines• Vaccines are parts of a pathogen or

whole organisms that are given to humans or animals by mouth or by injection to stimulate the immune system.

• When people or animals are vaccinated, the immune system recognizes the vaccine as antigen and produces antibodies and memory B cells.

Vaccines

• Vaccines• Four major strategies

are used to make vaccines:

1. Subunit vaccines2. Attenuated vaccines3. Inactivated (killed)

vaccines4. DNA vaccines

Vaccines

• Vaccines• Subunit vaccines• Subunit vaccines are made by injecting

portions of viral or bacterial structures, usually proteins or lipids from the microbe, to which the immune system responds.

• EX: Vaccines for hepatitis B, anthrax, tetanus, and meningococcal disease.

• http://library.thinkquest.org/20994/data/task8-2.html

Vaccines

• Vaccines• Attenuated vaccines• Attenuated vaccines involve using live

bacteria or viruses that have been weakened (attenuated) by aging or alteration of growth conditions.

• Attenuation prevents replication after the vaccine is introduced into the recipient.

• EX: Vaccines for MMR, tuberculosis, cholera, Saban polio, and chickenpox.

Vaccines

• Vaccines• Inactivated vaccines• The pathogen is killed and

the dead microorganism is used for the vaccine.

• EX. Vaccines for rabies, influenza, DPT, and Salk polio.

Vaccines

Vaccines• Vaccines• DNA Vaccines• DNA vaccines have demonstrated

that injecting small pieces of DNA from a microbe create an antibody response.

• DNA vaccines are composed of bacterial plasmids. Expression plasmids used in DNA-based vaccination normally contain two units: the antigen expression unit, followed by antigen-encoding and polyadenylation sequences and the production unit that is composed of bacterial sequences necessary for plamid amplification and selection

• DNA vaccines for HIV and malaria are in clinical trials.

Vaccines

• Vaccines• http://www.pbs.org/wgbh/pages/frontline/te

ach/vaccine/• Pros and cons of vaccination• http://www.hrsa.gov/vaccinecompensation/a

dverseeffects.pdf• Causality vaccines